This invention relates to an actuation system and more particularly to an actuation system having a no-back device.
Modern aircrafts are commonly equipped with actuators containing no-back devices. These actuators are subjected to aerodynamic loads resulting from the distribution of loads in the aircraft, from the trajectory of the aircraft, and from the flight conditions. No-back devices are employed in actuators of mechanical drive systems where it is necessary to prevent an aerodynamic load, from back driving the system in the event of a structural failure or disconnect of the input shaft to an actuator. A typical no-back device has a releasable brake associated with an output shaft as well as an input shaft connected to a prime mover. A coupling between the input shaft and output shafts operates in response to the transmission of torque from the output shaft to the input shaft to prevent movement of the output shaft, and assure that the element associated with the output shaft will remain in the position in which it was originally placed by operation of the prime mover.
The functionality of the no-back device is critical in instances where it is required. A failure of a no-back device is potentially dangerous since a shaft could be driven by the aerodynamic forces acting on the element to be actuated. The element would then not be held in the desired position, and could flutter rendering the aircraft unstable. It is therefore desirable to develop a system that easily and efficiently allows a mechanic to verify that the no-back device in an actuator is functioning properly.